On Fri, 3 Jul 2020 at 03:07, Random832 <random832@fastmail.com> wrote:
On Wed, Jul 1, 2020, at 08:23, Joao S. O. Bueno wrote:
> collections.mixins.SlicedSequence that would override `__delitem__`,
> `__setitem__` and `__getitem__` and
> handle slices could pair up with the "ComparableSequence" - people
> could use these "a la carte", and
> no backwards compatibility would be hurt.

This one raises the question of where you put the single-item accessors.

Really - I think I had worked on this once, but the slicing support was via decorators.

And sliced __delitem__ may be difficult to implement efficiently without knowing the internals of the sequence type.
Indeed, as would __setitem__ inserting  asequence larger than the target slice - (or shorter).
There are log of corner cases there hard to get right. 

But, yes, it would be so inefficient that probably it is better left for a 3rdy party package than the stdlib.
So - let's just drop these out of the proposal and maybe check if Sequence.__eq__ is worth it. 

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